Applicator Having a Microstructured Surface

ABSTRACT

The invention relates to a bristle carrier and bristles ( 1 ) formed thereon, the surface of the bristles ( 1 ) being microstructured at least in segments, in that a plurality of grains ( 2, 3 ) protrude haphazardly from the bristle core ( 4 ) in the region of the microstructured surface and are connected to the bristle core ( 4 ) only along less than 40%, preferably less than 35% of the outer surface thereof, and comprise an average diameter (ØM 1 , ØM 2 ) of less than or equal to 125 μm, preferably less than or equal to 90 μm.

OBJECT OF THE INVENTION

The invention preferably relates to an applicator comprising bristleshaving a microstructured surface. The invention further relates to anoption for applicators without bristles.

TECHNOLOGICAL BACKGROUND

In the field of applicators with bristles, a fundamental differentiationis made between wire-core applicators, wherein bristles in the form ofshort filaments are held clamped between two core wires twistedtogether, and injection-molded applicators, wherein the core of theapplicator is produced with the bristles formed thereon by means ofinjection molding. An individual bristle cavity is thereby provided foreach bristle, in which the plastic material is enclosed for forming thebristle.

Even for injection-molded bristles, a significant problem is that thesurface of the bristle is quite smooth and therefore the storagecapacity for the corresponding cosmetic material remains limited. Forthis reason, it has previously typically been attempted to improve thestorage capacity of an applicator by means of various embodiments of thespaces between the bristles. Depots are created between the bristles inwhich increased amounts of material can be stored.

Other proposals relate to using a flocking rather than bristles, saidflocking being very absorbent and therefore able to store a significantamount of material. Such applicators are disadvantageous, however, whereit is not only necessary to transfer a larger quantity of cosmeticmaterial, but also combing or curling is desired, such as for mascaraapplicators. The adhesive used for flocking is also disadvantageous.Said adhesive causes a disadvantageous adhesion of small pieces offlocking, whereby the production of a precisely defined surface finishonly slightly dependent on random chance is impeded. The adhesive alsomakes useless any profiling already provided on the raw part by fillingin said profiling.

For this reason, bristles have been proposed by PCT applicationPCT/EP2015/067694, having solid particles embedded in the plastic matrixthereof during injection molding, said particles partially protrudingoutward past the plastic surface of the injected bristles. Thistechnology as such is very promising in function. For some applications,there is a certain disadvantage in said technology, in that varying theamount by which the solid particles protrude and the protruding geometryis difficult or impossible.

OBJECT OF THE INVENTION

In this context, the object of the invention is to achieve furtherimprovement and adjustability of the material storage capacity of thebristles.

The Object Achieved According to the Invention

The object is achieved according to the invention by an applicatorhaving a bristle carrier and bristles formed thereon. The bristles arecharacterized in that the surface thereof is microstructured. Themicrostructuring can be applied only in segments, for example in theform of local rings enclosing the bristle in the circumferentialdirection, or of local stripes extending along the bristle in thedirection of the longitudinal axis thereof. Most of the surface of thebristle is preferably microstructured, ideally the entire bristle.

The microstructuring occurs in that a plurality of grains protrudehaphazardly from the bristle core in the region of the microstructuredsurface. Haphazard protruding in the sense of the invention isunderstood to mean a random arrangement, in contrast to an alignedarrangement in rows or matrix-like fields or having a recurring pattern.

Said grains are characterized in that less than 40%, or preferably lessthan 35%, of the original free exterior surface thereof is connected tothe bristle core. The unconnected part of the surface protrudes freelyoutward and is therefore available for coating with the cosmeticmaterial.

The individual grains have an average diameter of 125 μm and preferablyan average diameter of 90 μm.

The average diameter of a grain is defined according to the inventionhere and everywhere as the diameter of a theoretical least sphere inwhich said grain can still be inscribed when theoretically disconnectedfrom the bristle core.

Speaking figuratively, the teaching of the invention is that the surfaceof a bristle is equipped with a certain quantity of “sprinkles”providing a largely controllable degree of roughness. The latter can beutilized intentionally for improving the coatability of the bristle withand/or the adhesion of the cosmetic mass on the bristle. In this manner,the storage capacity of the bristle surface can be purposefully adaptedto the corresponding cosmetic to be transferred by the bristle and therheological properties thereof.

Said surface structure can no longer be controlled by means of injectionmolding, of course, as such microstructuring would not be feasible. Themicrostructuring can, however, be produced well by means of thethree-dimensional plastic printing process or laser sintering ofplastics, known from the field of “rapid prototyping”, or in general bymeans of a primary layer forming process. Only the fusing times need tobe controlled in a skilled manner here, so that a largely smooth surfaceis not produced by fusing. Instead, the laser beam must be directedand/or focused so as to bond the grains used as the raw material onlypartially and locally to the bristle core by means of correspondinglocal fusing. Control can further be achieved by means of the averagegrain size of the granulate used.

Further Object of the Invention

A further object of the invention is to achieve further improvement andadjustability of the material storage capacity of applicators withoutbristles.

The Further Object Achieved According to the Invention

The further object is achieved by an applicator having a particularlystructured cosmetic application surface. A cosmetic application surfaceis understood here to be a surface associated with a delicateapplicator, the actual applicator body thereof (without handle andclosure cap) fitting into a theoretical cylinder having a radius of 2 cmand a length of 8 cm.

Said cosmetic application surface can be a surface made of individualsurfaces formed by bristle surfaces, together with the individualsurfaces present between the bristles in the region of the bristlefield. Said surface, however, is preferably here the cosmeticapplication surface of an applicator designed having no protrudingbristles, fingers, or pins.

The cosmetic application surface according to the invention ischaracterized in that the surface thereof is microstructured. Themicrostructuring can be applied only in segments, for example in theform of local rings enclosing the applicator in the circumferentialdirection, or by local islands preferably disposed as a regular patternon the entire cosmetic application surface. The cosmetic applicationsurface is preferably mostly microstructured, ideally the entirecosmetic application surface.

The microstructuring occurs here as well in that a plurality of grainsprotrude haphazardly from the bristle core in the region of themicrostructured surface. Haphazard protruding in the sense of theinvention is understood to mean a random arrangement, in contrast to analigned arrangement in rows or matrix-like field or having a recurringpattern.

Said grains are characterized in that less than 40%, or preferably lessthan 35%, of the original free exterior surface thereof is connected tothe bristle core. The unconnected part of the surface protrudes freelyoutward and is therefore available for coating with the cosmeticmaterial.

The individual grains have an average diameter of ≤125 μm and preferablyan average diameter of ≥90 μm. The average diameter of a grain isdefined according to the invention here and everywhere as the diameterof a theoretical least sphere in which said grain can still be inscribedwhen theoretically disconnected from the bristle core.

Speaking figuratively, the teaching of the invention is that thecosmetic application surface is equipped with a certain quantity of“sprinkles” providing a largely controllable degree of roughness. Thelatter can be utilized intentionally for improving the coatability ofthe cosmetic application surface with and/or the adhesion of thecosmetic mass on the cosmetic application surface. In this manner, thestorage capacity of the cosmetic application surface can be purposefullyadapted to the corresponding cosmetic to be transferred by the cosmeticapplication surface and the rheological properties thereof.

Said surface structure can no longer be controlled by means of injectionmolding, of course, so that the production notes given above apply hereas well.

Preferred Potential Embodiments

In the two cases indicated above, it has been found to be advantageousthat the set of grains used for microstructuring the surface comprisesfirst grains, or is even made entirely thereof, having an averagediameter of greater than or equal to 30 μm and preferably greater thanor equal to 40 μm. This is because such grains, small but not too small,are able in most cases to produce particularly good contact between thetypical cosmetic material and the bristle microstructured by means ofsaid grains.

It can be advantageous in some cases that a plurality of second grainsare distributed between or at the first grains, protruding from thebristle core according to the invention and/or protruding from the firstgrains in a corresponding manner, the average diameter thereof being 30μm or preferably 25 μm. Spreading such second, smaller bodies can helpto further increase the wettable surface and then delay dripping ofcritical cosmetic substances, for example.

As discussed above, the bristle need not comprise microstructuringaccording to the invention over the entire surface thereof. It can besufficient if the bristle surface comprises an area of 1 mm² in eachcase at which at least five, preferably at least eight grains protrudein the manner indicated above.

For microstructuring over a large area, said dimension is ideallymaintained over the entire or at least most of the microstructuredsurface.

It has been found to be particularly advantageous if an undercut ispresent at least locally, preferably of at least 70% all around, betweenthe point at which the first grain is connected to the bristle corealong the circumference thereof or at the circumference thereof, and themaximum circumference of the first grain protruding outward. In thisway, said grain can dip like an anchor positively into the layer ofcosmetic material carried by the bristle and thereby ensure goodretention of the cosmetic material.

The retaining function implemented by the microstructured surfacerelative to the cosmetic material can be further improved in that aplurality of grains comprising an undercut of the type described can befound over an area of 1 mm² and are disposed directly adjacent to eachother. The grains should thereby not touch each other, but rather bespaced a very small distance apart above—as seen substantially in theradial direction—the region in which said grains are bonded to a bristlecore, from where the spacing thereof increases up to the region at whichsaid grains are bonded to the core.

It is particularly advantageous if the microstructuring of the surfaceis controlled so that least 25%, preferably at least 30%, of the exposedsurface of the bristle is in the region of a radial undercut. The term“exposed surface” thereby defines a surface freely accessible from theoutside along any path. Said path need not be a straight path, but apath not crossed by any other grains, but always running through the airspace. An undercut is a free space from which no straight-line pathleads out in the purely radial direction (perpendicular to thelongitudinal axis of the bristle.)

It can be particularly advantageous not only to equip the bristles withthe microstructure described above but optionally also to equip thebristle carrier, in the region thereof free of bristles and lyingbetween the surrounding bristles protruding from the bristle carrier,with a microstructured surface of the type described above. In thismanner, the coatability and material storage capacity of the bristlecarrier can also be adjusted.

Applicators characterized in that the applicator core or bristle carrieris a cast, extruded, or injection-molded plastic part, or a metal parthaving bristles applied thereto in layers, have proven to beparticularly advantageous. Particularly inexpensive production can beachieved if the plastic injection-molded part or the metal part isalready equipped with a set of bristles (e.g., by encapsulating orembedding filaments) and only additional bristles or specializedbristles are added by means of a primary layer forming process, and/orexisting bristles are provided with the microstructured surfaceaccording to the invention by means of simple coating using the primarylayer forming process.

This is particularly also the case where applicators having no bristles,such as for use as a lip applicator, are provided with themicrostructured surface according to the invention.

It is particularly advantageous here to use applicator blanks formed byinjection molding or another primary forming process, in order toproduce a finished applicator by applying the microstructured surfaceaccording to the invention to the blank by means of the primary layerforming process. To the extent that the microstructured surfaceaccording to the invention is to be preferably applied only locally,recesses are preferably provided in the applicator blank and filled inby the primary layer forming process. Particularly good anchoring of themicrostructured surfaces according to the invention can thereby beachieved, as well as a sharp boundary between the microstructuredregions and regions having conventional surface properties.

Protection is also requested for the production of such an applicator,and/or for the production of an applicator having the structured surfaceaccording to the invention.

Protection is further claimed for an applicator characterized in thatpart of the bristles are injection-molded bristles, between whichadditional bristles have been installed subsequently by means of aprimary layer forming process, and for a method for producing such anapplicator.

Therefore protection is also claimed for methods for producing anapplicator, including of the type described above, characterized in thatan applicator core or bristle carrier is produced as an injection-moldedpart and subjected to a treatment and preferably a corona treatmentprior to applying the bristles in layers, said treatment increasing thesurface tension of said applicator or bristle carrier and preferably setup for increasing the polar portion of the surface tension.

It is thereby particularly advantageous if the surface tension of thematerial of said applicator or bristle carrier is adjusted to be greaterthan the surface tension of the material being applied.

Protection is also claimed, in conjunction with the previously claimedfeatures but also as isolated protection completely independent ofpreviously claimed features, for an applicator having an edge layercomprising a proportional contact area of less than or equal to 50%measured to a depth of 2/10 mm and preferably to a depth of 4/10 mm, atleast wherever said layer is structured beyond the surface roughness,said roughness ranging up to +/− 2/1000 mm. The measurement is performedin that a straight line is placed on the outermost surface of the edgelayer, optionally from one surface peak to the immediately adjacentsurface peak. From there, a measurement is made radially inward by saidamount, namely 2/10 mm or preferably 4/10 mm. The proportion of “air”measured within said strip is, on average, at least equal to or greaterthan the proportion of plastic measured within said strip.

In general, the applicator is preferably implemented as a singlematerial where said applicator has the surface structure according tothe invention, that is, is made of a single plastic material.

Further modes of action, advantages, and potential embodiments arisefrom the following embodiment example described in the figures.

LIST OF FIGURES

FIG. 1 shows an embodiment example of a bristle microstructuredaccording to the invention in the region of the tip thereof, where asubstantial part of the tip has broken off, depicted by the view of thehatched bristle core.

FIG. 2 shows a detail magnification from the left flank of themicrostructured bristle tip according to FIG. 1.

FIG. 3 illustrates the substantial dimensions of a bristle according tothe invention and the lateral deflectability thereof.

FIG. 4 illustrates the application of the invention to a lip applicatorhaving no bristles whatsoever.

FIG. 5 shows the application of the invention to another lip applicatoralso having no bristles whatsoever but also having a macroscopicstructure, wherein a partial section view having the front part cut awayis depicted here.

DESCRIPTION OF EMBODIMENT EXAMPLES First Embodiment Example

FIG. 1 shows the top part of a bristle made of plastic for forming theedging of a bristle applicator according to the invention.

The length LAE of a bristle according to the invention is typicallybetween 3 mm and 10 mm. The maximum bristle diameter DB of a bristleaccording to the invention is typically between 0.01 mm and 0.05 mm.

The bristle according to the invention is preferably flexible, that is,able to be deflected laterally. The flexibility is typically greatenough that the tip of the bristle can be reversibly elasticallylaterally deflected by the forces arising during application by at leastfour times, preferably six times, the amount BT of the maximum bristlediameter (measured above any fillet where the bristle transitions intothe bristle carrier), as shown in FIG. 3.

It is particularly advantageous if the bristle tapers down from the baseto the tip thereof, preferably at an average taper angle AP of 0.2° to10°.

Applicators according to the invention typically have between 75 and 750bristles of the type described here. It is further noted that theplastic of the bristles need not be identical to the plastic of thebristle carrier, even if the bristles and bristle carrier transitioninto each other as a single part. It can further be advantageous toproduce the bristle from different plastics along different regions. Ithas been found to be advantageous, for example, to produce the bristlesfrom a particularly elastic plastic in the base region thereof, in orderto produce a type of joint at said point about which the bristle can bepivoted back and forth.

For the bristle shown in FIG. 1, only the region of the bristle tip hasthe microstructuring according to the invention. Further isolatedregions of the bristle could additionally have such microstructuring.For example, the one or more rings spaced apart from each other asdescribed above and enclosing the circumference of the bristle couldalso be thus equipped. For some other applications, it is particularlyadvantageous to provide the entire bristle with the microstructuringaccording to the invention.

Second Embodiment Example

A second embodiment example of the invention is shown in the top half ofFIG. 4, and a third embodiment example in the bottom half of FIG. 4.Depicted is a lip applicator. The blank of said lip applicator ispreferably produced as an injection-molded part. The lip applicator hasthen been equipped with a microstructured surface according to theinvention in segments in the manner described above.

For the case of the second embodiment example, the end face 6 of the lipapplicator, intended for taking up from the store a certain quantity ofthe cosmetic to be applied and for applying the same to the lips, hasbeen equipped according to the invention.

As can be seen here, first regions 7 microstructured according to theinvention are provided at the edge of the end face 6. Said regions 7 arepreferably microstructured such that the cosmetic to be applied adheresparticularly well thereto. In this manner, smudging can be prevented ordelayed, as it would otherwise be likely to occur that a certain amountof the viscous cosmetic received adhesively by the end face at firstwould slip off and then drip over the edge of the end face.

The adhesion can be further improved if second (typically 5 to 25 incount) microstructured regions 8 are also present. Said furthermicrostructured regions 8 are preferably implemented as islands separatefrom each other, each of which ideally individually comprises acircular, oval, elliptical, or plum-shaped surface extent.

The microstructured surface in the present embodiment example preferablytakes up only a minority of the surface intended as the applicationsurface (typically the end face).

The third embodiment example is depicted in the bottom half of FIG. 4.

For the case of the third embodiment example, the end face 6 of the lipapplicator, intended for taking up from the store a certain quantity ofthe cosmetic to be applied and for applying the same to the lips, hasalso been equipped according to the invention. For this purpose,microstructured regions 9 are present, here having the shape ofconcentric or equidistantly spaced rings. Conventional regions 10 canalso be provided in the shape of rings between the microstructuredregions.

The present arrangement can also have an extremely positive effect onthe mass storage and mass discharge behavior. For a corresponding designof the surface structure according to the invention, the microstructuredregions 9 can take up an increased quantity of the cosmetic from thestore and transport the same to the skin area to be treated. Duringapplication, part of the mass stored by the microstructured regions isthen first forced into the conventional regions and then particularlyquickly transferred therefrom to the skin area to be treated.

It is noted that the microstructured surface according to the inventionand a macroscopic surface structure can overlap spatially and canpreferably also reinforce each other in effect. This is evident from thefourth embodiment example, as illustrated in FIG. 5.

Macroscopically raised regions 11 are implemented here on the lipapplicator. The structures here protrude in any case by at least 0.8 mm(FIG. 5, dimension A) at least in a direction opposite the immediatesurrounding area thereof (FIG. 5, dimension W) spaced apart by a maximumof 3 mm on both sides along said direction. Because the raised region ofFIG. 5 is additionally provided with the microstructured surfaceaccording to the invention, the material storage capacity of the valleys12 is significantly increased.

Depending on the rheology of the cosmetic material to be applied, it canbe sensible to alternatively equip only the valleys 12 with themicrostructured surface according to the invention, or to additionallyequip the valleys 12 with the microstructured surface.

Details of the Microstructuring Used for the Embodiment Examples

The details of the microstructuring according to the invention (for abristle in the example) can be seen well in FIG. 2.

As is evident, the bristle has a bristle core 4. The bristle core 4 canhave a homogenous microstructure or a grained microstructure. Ahomogenous microstructure can also mean that local air inclusions orlocal gaps are present (not shown in the drawing), as long as saidfeatures do not reduce the strength and elasticity of the bristle to theextent that the bristle no longer exhibits the flexibility indicatedabove.

The embodiments below apply analogously to an applicator withoutbristles. Said applicator can also comprise a corresponding applicatorcore having a homogenous microstructure or a grainy microstructure. Ahomogenous microstructure, in this case, can also mean that local airinclusions or local gaps are present (not shown in the drawing) as longas said inclusions or gaps do not substantially reduce the strength andelasticity of the bristle.

The following applies analogously for both embodiment examples:

As is evident, a plurality of grains 2, 3 protrude from the surface ofthe bristle in the microstructured region. As can be seen well in FIG.2, said grains have a free outer surface, that is, the outermost locallimit of the outer surface forming the bristle here. The shortesttheoretical intersecting surface area by means of which each grain couldtheoretically be cut off from the bristle core 4, is less than 40% ofthe free outer surface of each grain for the grains 2, 3 essential tothe invention.

The grains have a certain size. How this size is determined can also beseen well in FIG. 2. A theoretical sphere is formed in which the grainto be measured is inscribed. The radius of the smallest possible spherein which the grain (as measured optically) can be inscribed is theaverage diameter ØM of the grain. Said average diameter ØM is ≤125 μmfor the grains according to the invention.

Differentiation is thereby preferably made between larger first grains 2and smaller second grains 3. Said two types of grains can also be seenwell in FIG. 2. The larger grains 2 are characterized in that saidgrains have an average diameter ØM of at least 30 μm.

In contrast, the preferably additionally present, smaller grains 2 arecharacterized in that said grains have an average diameter ØM of <30 μmand preferably even <25 μm.

As can be easily understood from FIG. 2, the microstructuring accordingto the invention forms a wildly rugged surface having many undercutssized so as to be filled in by the cosmetic material. In this manner,many protrusions and recesses result, at which the cosmetic material canadhere. Therefore, even if the cosmetic material is set up so as to noteasily coat a smooth surface smoothly, said surface can be well loadedwith the cosmetic material.

The retaining effect can be further increased if the production methodis set up so that grains occur immediately adjacent to each other but donot make contact.

Said grains are then advantageously bonded to the bristle core such thatthe spacing again increases from the point at which said grains arespaced apart by the least distance KA from each other to the region Bwhere said grains are bonded to the bristle core.

In this manner, opposing undercuts are formed and exhibit particularly agood retention effect.

Such an arrangement is shown in FIG. 2 just above the center of thefigure and is marked with reference numbers.

Wherever an applicator core or bristle carrier is produced as aprefabricated part, particularly as an injection-molded part, in orderto apply a structured surface or bristles thereto in layers it issensible to subject the surface of said blank to a treatment forpreparing the same in order to ensure good adhesion of the material tobe applied. This applies not least when said blank is made ofpolyethylene, polypropylene, and polyester.

Suitable treating methods here include corona treatment and possiblyalternatively fluoridation or flame or plasma treatment. The objectiveof said methods is to increase the polarity of the surfaces, whereby thecoatability and chemical affinity are increased significantly.

Corona treatment is typically performed “in line” at the end of theproduction process for the blank. The blank, such as a cylindricalbristle carrier without bristles, is thereby subjected to a high-voltageelectrical discharge. Said discharge occurs between a grounded, polishedplate or roller made of steel or aluminum and an insulated electrodenearby.

Depending on the field of application, the use of an insulated rollerand non-insulated electrodes is also possible.

The bristle carrier thereby rotates about the electrode. The electrodeis supplied by a high-frequency generator at an alternating voltage of10 to 20 kV and a frequency between 10 and 60 kHz.

REFERENCE LIST

-   1 Bristle-   2 First grain-   3 Second grain-   4 Bristle core-   5 Undercut-   6 End face of the lip applicator (application surface)-   7 (First) region having a microstructured surface-   8 (Second) region having a microstructured surface-   9 (Additional) region having a microstructured surface-   10 Conventional region-   11 (Macroscopically) raised region-   12 Valley-   R Radial direction-   B Region in which a grain is bonded to the bristle core 4-   KA Least distance between 2 directly adjacent grains-   L Longitudinal axis of a bristle-   ØM Average diameter of a grain-   ØMax Maximum circumference of a grain-   LAE Bristle length-   DB Bristle diameter, max-   BT Amount by which a bristle can be reversibly deflected-   AB Average cone angle/taper angle of a bristle

A Dimension by which the raised region is raised W Dimension of distancebetween the raised region and a non-raised region (valley)

1. An applicator having a bristle carrier and bristles (1) formedthereon, characterized in that the surface of the bristles (1) ismicrostructured at least in segments, in that a plurality of grains (2,3) protrude haphazardly from the bristle core (4) in the region of themicrostructured surface and are connected to the bristle core (4) onlyalong less than 40%, preferably less than 35% of the outer surfacethereof, and comprising an average diameter (ØM1, ØM2) of less than orequal to 125 μm, preferably less than or equal to 90 μm.
 2. Anapplicator having a cosmetic application surface, characterized in thatthe cosmetic application surface is microstructured at least insegments, in that a plurality of grains (2, 3) protrude haphazardly fromthe cosmetic application surface in the region of the microstructuredsurface and are connected to the cosmetic application surface only alongless than 40%, preferably less than 35% of the outer surface thereof,and comprising an average diameter (ØM1, ØM2) of less than or equal to125 μm, preferably less than or equal to 90 μm.
 3. The applicatoraccording to claim 1 or 2, characterized in that the grains (2, 3)comprise first grains (2) or are made entirely of first grains (2)having an average diameter (ØM1) of at least 30 μm and preferably atleast 40 μm.
 4. The applicator according to any one of the claims 1through 3, characterized in that a plurality of second grains (3) arehaphazardly distributed between or on the first grains (2) and protrudefrom the bristle core (4) according to claim 1 and/or in a correspondingmanner from the first grains (2), and the average diameter (ØM2) thereofis less than or equal to 30 μm, preferably less than or equal to 25 μm.5. The applicator according to any one of the claims 1 through 4,characterized in that the bristle surface comprises in any case an areaof 1 mm² at which at least 5, preferably at least 8 first grains (2)protrude as described above.
 6. The applicator according to any one ofthe claims 1 through 5, characterized in that an undercut (5) is presentat least locally, preferably of at least 70% all around, between thepoint at which a first grain (2) is connected to the bristle core (4)along the circumference thereof and the maximum circumference (Max) ofthe first grain (2) protruding outward.
 7. The applicator according toclaim 6, characterized in that on an area of 1 mm², a plurality ofgrains (2) having an undercut and directly adjacent to each other arepresent, and the grains (2) do not touch each other, but rather theleast distance (KA) between said grains occurs above the region (B) atwhich said grains are bonded to the bristle core—substantially as seenin the radial direction (R)—from which point the distance between saidgrains increases until the region (B) at which said grains are bonded tothe bristle core (4).
 8. The applicator according to any one of thepreceding claims, characterized in that at least 30% of the free surfaceof the microstructured bristle segment is present in the region of aradial undercut (5).
 9. The applicator according to any one of thepreceding claims, characterized in that the bristle carrier comprises afree surface in a region without bristles, between surrounding bristles,and is microstructured at least in segments, in that a plurality offirst grains protrude from the bristle core in the region of themicrostructured surface and are connected to the bristle core along lessthan 40%, preferably less than 30%, of the outer surface thereof, andcomprise an average diameter of less than or equal to 125 μm, preferablyless than or equal to 90 μm.
 10. The applicator according to any one ofthe preceding claims, characterized in that the applicator core orbristle carrier is an injection-molded plastic part or a metal partwithout bristles or having bristle stubs, having bristles appliedthereto in layers.
 11. The applicator according to claim 9,characterized in that part of the bristles are injection-molded bristlesbetween which additional bristles have been installed subsequently bymeans of a primary layer forming process.
 12. An applicator, preferablyaccording to any one of the preceding claims, characterized in that thecarrying proportion of the edge layer of the applicator is 50% measureddown to a depth of 2/10 mm and preferably to a depth of 4/10 mm.
 13. Amethod for producing an applicator according to claim 10, characterizedin that an applicator core or bristle carrier is produced as aninjection-molded part and subjected to a treatment and preferably acorona treatment prior to applying the bristles in layers, saidtreatment increasing the surface tension of said applicator or bristlecarrier and preferably set up for increasing the polar portion of thesurface tension.
 14. The method according to claim 10, characterized inthat the surface tension of the material of said applicator core orbristle carrier is adjusted to be greater than the surface tension ofthe material being applied.